Fix broken code samples (indent, spaces, failing doctest)

docs/src/tutorial/cdef_classes.rst

@@ -135,7 +135,7 @@ Attributes in cdef classes behave differently from attributes in regular classes
       # Available in Python-space:
       property period:
           def __get__(self):
-              return 1.0 / self. freq
+              return 1.0 / self.freq
           def __set__(self, value):
-              self. freq = 1.0 / value
+              self.freq = 1.0 / value
       <...>

docs/src/tutorial/clibraries.rst

@@ -440,7 +440,7 @@ The following listing shows the complete implementation that uses
                     raise IndexError("Queue is empty")
             return value
 
-        cdef int pop(self) except? -1:
+        cpdef int pop(self) except? -1:
             if cqueue.queue_is_empty(self._c_queue):
                 raise IndexError("Queue is empty")
             return <int>cqueue.queue_pop_head(self._c_queue)